A triggering circuit for triggering series-connected spark gaps

ABSTRACT

A chain of series-connected spark gap piles have two grading chains in parallel therewith with connections therebetween. An arrangement is provided for triggering one of the spark gap piles. When this pile is triggered, all the spark gap piles in the chain spark over if the voltage over the spark gap piles between two connections from a grading chain is not less than the spark-over voltage for each of these piles. One grading chain is formed of a number of resistors and capacitors in parallel connected across each end gap pile and each pair of other gap piles, and the other grading chain is formed of resistors in the chain between the pairs of gap piles and circuits formed of a capacitor and a resistor in parallel with each pair of gap piles.

O United States Patent 1151 3,662,215 Schei 1 51 May 9, 1972 541 A TRIGGERING CIRCUIT FOR 3,393,338 7/1968 Lee et a1. ..315/36 x 3,418,530 12/] Cheever 15/36 X 3,496,409 2/1970 Connell ....315/36 X SPARK GAPS 3,510,726 5/1970 Harder ..315/189 [72] Inventor: Asle Schei, Ludvika, Sweden FOREIGN PATENTS OR APPLICATIONS 1731 Assignee Ak'iem'aleh 940 978 11/1963 Great Britain 315/36 Vasteras, Sweden I 22 Filed; Man 25 197 Primary Examiner-John W. Huckert Assistant E.\'aminerAndrew J. James [21] Appl. No.: 128,195 Attorney-Jennings Bailey, Jr.

Related US. Application Data 57 ABSTRACT Continuation of 1969 A chain of series-connected spark gap piles have two grading fibandonedchains in parallel therewith with connections therebetween. An arrangement is provided for triggering one of the spark gap [30] Foreign Application Priority Data piles. When this pile is triggered, all the spark gap piles in the chain spark over if the voltage over the spark gap piles Feb. 28, 1968 Sweden ..2533/68 between two connections from a grading chain is no! less than the spark-over voltage for each of these piles. One grading [52] U.S.Cl ..3l5/l89, 3l5/35,315/36, chain is formed of a number of resismrs and capacitors in 315/241, 328/9 parallel connected across each end gap pile and each pair of [51] Int. Cl ..H05b 37/00, HOSb 39/00 other gap piles, and the other grading chain is formed of re- [58] Field of Search ..315/35, 36, 189, 241; 328/8; sistors in the chain between the pairs of gap piles and circuits 313/231.1, 325 formed of a capacitor and a resistor in parallel with each pair of gap piles. [56] References Cited 4 Claims, 1 Drawing Figure UNITED STATES PATENTS 3,353,059 11/1967 Bufia et a1 ..328/9 X PATENTEDMY 9 I912 3.662.215

INVENTOR. ASLE 8CHE\ MW G BACKGROUND OF THE INVENTION Field of the Invention For various purposes, for example with certain types of over-voltage protection devices, it may be valuable for seriesconnected spark gap piles to spark over for a voltage which is lower than the total normal spark over-voltage of the seriesconnected gap piles.

SUMMARY OF THE INVENTION The present invention relates to a means for triggering series-connected spark gap piles so that by triggering one of the gap piles the entire spark gap chain can be made to spark over-for a voltage which is greater than or equal to half the spark over-voltage for the whole gap arrangement.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawing shows one example of a system according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The arrangement shown in the drawing consists of a spark gap chain and a first and second grading chain. The spark gap chain consists of a number of series-connected spark gap stack piles G which are preferably equal and have the same spark over-voltage. Resistors R are connected at certain points in the chain. In the shown embodiment of the invention such a resistor is connected between the two outermost gap piles at both ends of the chain, whereas otherwise groups of two series-connected gap piles are separated by one resistor. The resistance of the resistors may vary and can even attain the value zero. It may also vary from resistor to resistor.

The first grading chain consists of a series connection of the resistors R in the spark gap chain and also a number of parallel circuits each consisting of a capacitor and a resistor. The grading chain has one such parallel circuit at each end consisting of a capacitor 2 C, and a resistor R,,,,,

The other parallel circuits consist of a capacitor C, and a resistor R,. The two outer parallel circuits are connected over a single spark gap pile G whereas all the other parallel circuits are connected over two series-connected spark gap piles.

The second grading chain consists of a number of seriesconnected parallel circuits, each consisting of a capacitor C and a resistor R Each of these circuits is connected over a resistor R and a spark gap Ci situated on each side of the resistor in the spark gap chain. Alternatively the central point of a resistor R, in the first grading chain may be connected to the connection point of the spark gap chain on the second grading chain. In such an arrangement the resistor R in the second grading chain can be omitted.

The two grading chains control the voltage over the spark gap chain both capacitively and resistively. Regarding the size relationship between the resistors R, and R which are in series with each other, it should be mentioned that R, is very much larger than R, and that the latter may even be zero.

Over one or more of the spark gap piles in the spark gap chain a triggering circuit T is connected, with the help of which the spark gap piles connected to the triggering circuit can be ignited. In the drawing the triggering circuit is shown connected to the lowermost spark gap pile which, from the point of view of insulation, is most advantageous. The triggering circuit consists of a voltage source B, a resistor R and a switch S.

If the voltage over the whole chain is U, this means that each of the capacitors C, and C, is charged to avoltage 2 U/n where n is the number of series-connected spark gap piles. By

supplying a triggering pulse to one or more of the ga piles, for example the lowest, so that it sparks over, all the vo tage over the lowermost capacitor C, will then be situated over the second gap pile from below so that the voltage over this gap pile is doubled and becomes equal to 2 U/n. If U is sufficiently high, greater than or equal to half the spark over-voltage for the series-connected gap piles, the second gap pile from below will spark over immediately after the lowermost gap pile has sparked over. When the second gappile has sparked over the third from below receives a voltage 2 um and sparks over. In this way the gap piles spark over successively upwards. The through-ignition time, that is the time from when the lowermost gap pile is triggered until the entire chain has sparked over, depends first on the construction of the gap pile since the capacitor C, in a circuit must be discharged before further gap piles can be ignited. The size of R however, is of no importance for the through-ignition time. A resistor R which is more high ohmic has, however, the advantage that the voltage distribution over the chain during the through-ignition process will be more linear.

With an arrangement according to the invention it is possible to build an over-voltage protection device having throughrunning, parallel legs in which the legs can be ignited successively with the required delay by taking the triggering pulse for a certain leg from a leg which has already sparked over.

What is claimed is:

l. A surge diverter comprising a chain of series-connected spark gap piles, first and second grading chains connected in parallel with said spark gap pile chain, each grading chain comprising a plurality of series-connected circuits, each of said circuits comprising a resistor and a capacitor in parallelconnection, each of said circuits, except the ones at the top and the bottom, in the first grading chain being connected across two spark gap piles in the spark gap pile chain, the connection points for the first and the second grading chains being equally and alternately distributed along the spark gap pile, said connection points constituting the only connections between each grading chain and the spark gap pile chain, a trigger circuit in the first grading chain connected across at least one spark gap pile, which forms a trigger spark gap pile, said trigger spark gap pile being in series with at least one further spark gap pile forming the part of the spark gap pile chain situated between two adjacent connection points for the second grading chain.

2. A surge diverter according to claim I, in which the spark gap pile chain also includes a number of resistors, evenly distributed within the spark gap pile chain.

3. A surge diverter according to claim I, in which the circuits of the first grading chain are series-connected with a number of resistors which are connected in the spark gap pile chain, each one between two connection points for said first grading chain.

4. A surge diverter according to claim 1, in which each circuit of the second grading chain is connected in parallel with two spark gap piles and a resistor situated between said two gap piles. 

1. A surge diverter comprising a chain of series-connected spark gap piles, first and second grading chains connected in parallel with said spark gap pile chain, each grading chain comprising a plurality of series-connected circuits, each of said circuits comprising a resistor and a capacitor in parallel-connection, each of said circuits, except the ones at the top and the bottom, in the first grading chain being connected across two spark gap piles in the spark gap pile chain, the connection points for the first and the second grading chains being equally and alternately distributed along the spark gap pile, said connection points constituting the only connections between each grading chain and the spark gap pile chain, a trigger circuit in the first grading chain connected across at least one spark gap pile, which forms a trigger spark gap pile, said trigger spark gap pile being in series with at least one further spark gap pile forming the part of the spark gap pile chain situated between two adjacent connection points for the second grading chain.
 2. A surge diverter according to claim 1, in which tHe spark gap pile chain also includes a number of resistors, evenly distributed within the spark gap pile chain.
 3. A surge diverter according to claim 1, in which the circuits of the first grading chain are series-connected with a number of resistors which are connected in the spark gap pile chain, each one between two connection points for said first grading chain.
 4. A surge diverter according to claim 1, in which each circuit of the second grading chain is connected in parallel with two spark gap piles and a resistor situated between said two gap piles. 